It is known that in extracts of thymus-gland tissues of humam beings and animals physiologically-active substances are present which provide a marked influence on the organism's growth and development, as well as on some immunological and metabolic processes (cf. Comsa, T., Amer. J. Med. Sci. 250, 79, 1965; Goldstein A. et al., J. Immunol., 140, 359, 1970; USSR Inventor's Certificate No. 459227, U.S. Pat. No. 4,120,951).
According to the data available from the literature, an extract from calf's thymus-gland (thymosin) is used for therapeutic purposes for the recovery of the function of the immunity system in human beings in the case of certain oncological and congenital immunodeficiency diseases (Goldstein A. et al., Transplant Proc. 7, 1 (Supp. 1), 681, 1975; Sakai et al, Cancer 36,3,973, 1975).
The administration of the thymus preparation to patients resulted in the recovery of disturbed immunological response of the organism Nevertheless, up till now the therapeutical efficiency of physiologically active substances obtained from the thymus-gland tissue and indications of their use in the medical practice have been studied but insufficiently.
Known in the art is a medicinal preparation from thymus-gland tissue--thymosin (cf. Goldstein A. et al., Proc. Nat. Acad. Sci., USA, 69, 7, 1800, 1972) which comprises a complex (about 30 components) of acid polypeptides with a molecular weight of 1,000 to 14,000 Dt (Hooper et al., Ann. N.Y. Acad: Sci., 249, 125, 1975). For the preparation of thymosin the following procedure is used (Hooper at al., 1975).
Calf's thymus is homogenized in a 0.15 M solution of NaCl, centrifuged at 14,000 g, the supernatant liquid is isolated and subjected to heating at the temperature of 80.degree. C., the formed precipitate is removed by filtration, while the remaining solution is added with 5 volumes of acetone. The resulting precipitate is dried on the filter, then again dissolved and salted out with ammonium sulphate first at a 25% saturation and then at a 50% saturation. The precipitate resulting from the salting-out operation is filtered, desalted in a column with Sephadex G-25 and lyophilized. At this stage of purification the obtained complex of polypeptides contained in the preparation has a most clearly pronounced biological activity--ability for stimulation of cell immunity (Hooper et al., 1975).
Further purification of the preparation causes reduction of its biological activity.
Thymosin produced by this method contains a complex of acid polypeptides with an isoelectric point of 3.5-6.7 and a molecular weight of 1,000-14,000 Dt with a substantial predominance of aspartic acid and glutamic acid amounting in total to 50% by weight of thymosin.
It should be noted, however, that this method for the preparation of thymosin is rather complicated and multi-staged (10 stages altogether). A number of operations are associated with certain difficulties in application of this process in industry (ultracentrifugation, the use of Sephadex packing). This method fails to provide a high yield of the medicinal preparation-thymosin. Thymosin also causes, in a number of patients, some side effects and allergic responses. The therapeutical efficiency of thymosin and possibilities for its application in medical practice have not been sufficiently studied.
It is an object of the present invention to provide a thymus-based medicinal preparation incorporating alkaline polypeptides and possessing a broad spectrum of the pharmacological action, while eliminating side effects and allergic responses upon its administration.
It is another object of the present invention to provide a method for producing a medicinal preparation from thymus which would ensure a high yield thereof by a simple process enabling isolation of alkaline polypeptides ensuring a high clinical efficiency in immunodeficient cases.